Ion exchanger for winning metals of value

ABSTRACT

The present invention relates to the use of monodisperse, macroporous anion exchangers of type I or type II in hydrometallurgical processes for winning metals of value.

The present invention relates to the use of monodisperse, macroporousanion exchangers of type I or type II in hydrometallurgical processesfor winning metals of value. Type I denotes resins whose adsorbing sitesare quaternary ammonium groups which are substituted by alkyl groups.Type II denotes resins in which the quaternary ammonium groups have notonly alkyl group(s) but at least one hydroxyalkyl group.

BACKGROUND OF THE INVENTION

Due to increasing industrialization in many parts of the world andglobalization, the demand for numerous metals of value such as cobalt,nickel, zinc, manganese, copper, gold, silver and also uranium hasincreased considerably in recent years. Mining companies and producersof industrial metals are attempting to satisfy this increasing demand bymeans of various measures. These include improving the productionprocesses themselves.

The metals of value relevant for industrial use are present inore-bearing rocks which are mined. The ore which is then present inrelatively large lumps is milled to give small particles. The materialsof value can be leached from these rock particles by a number ofmethods. The customary technique is hydrometallurgy, also referred to asthe wet method. If appropriate, the ore is subjected to a pretreatmentto produce soluble compounds (roasting, pyrogenic treatment) and theseare converted by means of acids or alkalis into aqueous metal saltsolutions. The choice of solvent is determined by the type of metal, theform in which it is present in the ore, the type of accompanying rock inthe ore (gangue) and the price. The most widely employed solvent issulphuric acid, and hydrochloric acid, nitric acid and hot concentratedsodium chloride solutions are also possible. In the case of ores havingacid-soluble accompanying materials, for example, copper ammoniacalsolutions can also be used, sometimes also under high pressure andelevated temperature (pressure leaching). Sodium hydroxide is used forthe winning of aluminium oxide; in the case of noble metals, alkalimetal cyanide solutions are used. As an alternative, the winning of themetals in hydrometallurgy can also be carried out by precipitation ordisplacement by means of a less noble metal (cementation), by means ofreduction by hydrogen or carbon monoxide under high pressure (pressureprecipitation) or by electrolysis using insoluble electrodes or bycrystallization (sulphates of copper, of zinc, of nickel or ofthallium), by conversion (precipitation) into sparingly solublecompounds such as hydroxides, carbonates or basic salts by means ofchalk, milk of lime or sodium carbonate solution.

U.S. Pat. No. 6,350,420 describes, for example, the treatment of the oreparticles with mineral acids such as sulphuric acid at high temperatures(e.g. 250-270° C.) under superatmospheric pressure (high pressureleaching). This gives a suspension (slurry) of the fine ore particles insulphuric acid, in which the leached metals are present in the form oftheir salts in more or less concentrated form.

As an alternative, the leaching of the metals from the rock can also beeffected by other methods. The type of process used depends on a numberof factors, for example on the metal content of the ore, on the particlesize to which the crushed ore has been milled or on apparatusconditions, to name only a few.

In the heap leaching process, relatively coarse ore particles having alow metal content are used.

In the agitation leaching process, finer ore particles (about 200 μm)having high metal contents are used in the leaching process.

However, the atmospheric leaching process or the biooxidation process isalso used for dissolving the metals from the ore. These processes arecited, for example, in U.S. Pat. No. 6,350,420.

The size of the milled ore particles to be used in these processes is inthe range from about 30 to about 250 μm. Because of the small size ofthe particles and the large amount of rock, a classic filtration of theparticles from the aqueous phase on filters is very costly. Separationby the gravitation principle in decanters by settling of the solid phasein very large stirred vessels is usually employed industrially. Toobtain good separation and a solution of materials of value which islargely free of particles, stirred vessels having a diameter of 50metres and more are used and a plurality of these are employed inseries. Large amounts of water are required and these are very expensivesince many mines are located in regions in which water is scarce(deserts). In addition, it is often necessary to use filtration mediawhich are expensive and pollute the environment to achieve betterremoval of the particles.

In hydrometallurgical plants and mines which are operated in largenumbers worldwide for the winning of materials of value such as gold,silver, nickel, cobalt, zinc and other metals of value, the processsteps of filtration and clarification account for a large proportion ofthe capital cost of the plant and the ongoing operating expenses.

Great efforts are therefore made to replace the abovementioned expensiveprocess steps by other less capital-intensive processes. New processesof this type are carbon in pulp processes for silver and gold and theresin in pulp (R.I.P.) process for gold, cobalt, nickel, manganese.

For example, U.S. Pat. No. 6,350,420 describes an R.I.P. process for thewinning of nickel and cobalt. A nickel-containing ore is treated withmineral acids in order to leach out the materials of value. Thesuspension obtained by means of the acid treatment is admixed with ionexchangers which selectively adsorb nickel and cobalt. The laden ionexchangers are separated from the suspension by means of screens.

The ion exchangers used in U.S. Pat. No. 6,350,420 are resins which aredescribed in U.S. Pat. No. 4,098,867 and U.S. Pat. No. 5,141,965.Suitable resins are accordingly Rohm & Haas IR 904, a strong basemacroporous anion exchanger, Amberlite XE 318, Dow XFS-43084, DowXFS-4195 and Dow XFS-4196.

The ion exchangers described in U.S. Pat. No. 4,098,867 and U.S. Pat.No. 5,141,965 contain variously substituted aminopyridine, in particular2-picolylamine, groups. All ion exchangers described there display aheterodisperse bead diameter distribution. In U.S. Pat. No. 5,141,965,the ion exchangers display bead diameters in the range 0.1-1.5 mm,preferably 0.15-0.7 mm, most preferably 0.2-0.6 mm. The ion exchangersdescribed in U.S. Pat. No. 4,098,867 display bead diameters in the range20-50 mesh (0.3 mm-0.850 mm) or larger diameters.

Rohm & Haas IR 904, a strong base macroporous anion exchanger, andAmberlite XE 318 are likewise heterodisperse ion exchangers having beaddiameters in the range 0.3-1.2 mm. In the examples, screens having meshopenings of 30 or 50 mesh (=300 to 600μ mesh opening) are used toseparate the laden ion exchangers from the rock particles and theleached solution.

In the case of uranium as material of value, it is mined either by opencast methods or underground. In the case of underground mining,mechanical cutting and, in the case of ores having a low uraniumcontent, in-situ leaching are used. The uranium present in the ore isseparated by physical and chemical processes from the remaining rock(liberated). For this purpose, the ore is comminuted (crushed, finelymilled) and the uranium is leached out. This is achieved by means ofacid or alkali with addition of an oxidant in order to convert theuranium from the very sparingly soluble chemical 4-valent state into thereadily soluble 6-valent form. In this way, up to 90 percent of theurnanium present in the ore can be recovered (seewww.nic.com.an/nip.htm).

Undesirable accompanying materials are removed from the slurry/solutionobtained in a plurality of purification steps by means of decantation,filtering, extraction, etc.

The uranyl ions are removed from the purified solution using anionexchangers.

The first publication DE 26 27 540 (=U.S. Pat. No. 4,233,272) disclosesa process for the selective separation of uranium by means of an ionexchanger from acidic solutions which additionally contain nickel, iron,arsenic, aluminium and magnesium. A chelating cation exchanger is usedhere, with both uranyl UO₂ ²⁺ and U⁴⁺ ions being separated off using8-12% strength sulphuric acid.

U.S. Pat. No. 4,430,308 describes a process for the winning of uraniumby means of a heated ion exchanger, with type II resins, for exampleDuolite 102 D®, Ionac A-550®, Ionac A-651®, IRA 410®, IRA 910® and Dowex2®, being able to be used for this purpose. All of these areheterodisperse, gel-like or macroporous ion exchangers based on styreneand divinylbenzene as crosslinker.

DD 245 592 A1 describes a process for removing uranium by means of anionexchangers, characterized in that heterodisperse anion exchangers whichare prepared by reaction of crosslinked alkyl acrylate copolymers withpolyamines are used.

DD 245 368 A1 relates to a process for separating off and recoveringuranium, in particular in the form of its uranium sulphato complexes bymeans of heterodisperse ion exchangers which are prepared from(methyl)acrylic ester copolymers and polyamines from the series ofhydroxyethyl-polyethylenepolyamines. Furthermore, DD 261 962 A1discloses a process for preparing heterodisperse ion exchangers havingamino groups and ortho-hydroxyoxime groups. In Example 1c of thisdocument, uranium is present in the form of anionic uranyl sulphatocomplexes and is bound on a heterodisperse anion exchanger which hasbeen prepared by the process mentioned.

DE 101 21 163 A1 describes a process for preparing heterodispersechelating exchangers which contain chelating groups of the formula—(CH)_(n)NR₁R₂ and are used for removing the heavy metals or noblemetals, for instance uranium. The patent DE 34 28 878 C2 discloses aprocess for recovering uranium in an extractive reprocessing procedurefor irradiated nuclear fuels. In this process, use is made of baseheterodisperse anion exchangers based on polyalkyleneepoxypolyaminehaving tertiary and quaternary amino groups of the chemical structureR—NH⁺(CH₃)₂Cl⁻ and R—NH⁺(CH₃)₂(C₂H₄OH)Cl⁻.

A disadvantage of the ion exchanger used in the prior art for thewinning of uranium and also those for the winning of cobalt or nickel isthe nonuniform loading of the ion exchanger with uranyl ions, whichleads to considerable losses. Due to the ion exchangers used, theseparation of the laden ion exchanger beads from the slurry via a screenresults in further product losses because part of the beads is lostthrough the sieve because of their small diameter. The consequences arelosses both of metal of value, for example uranium, but also of ionexchanger beads. Furthermore, the washing out of fine ore particlesremaining from the digestion process from the fine beads is very timeconsuming and requires large amounts of water. Finally, the ionexchangers to be used according to the prior art cause high pressuredrops and the nonuniform loading of the ion exchanger beads result inbroad mixing zones in the eluates in the elution of the metal of valuefrom the beads, which are disadvantageous for further uranium winning.

The solution to the problem and thus subject matter of the presentinvention is the use of monodisperse, macroporous, intermediate base orstrong base anion exchangers of type I or type II in the winning ofmetals of value.

The monodisperse anion exchangers to be used according to the inventionare preferably used in hydrometallurgical processes, particularlypreferably in resin in pulp processes (R.I.P. processes) or in in-situleaching processes or in the work-up of water containing metals ofvalue.

SUMMARY OF THE INVENTION

The invention therefore also relates to a process for winning metals ofvalue from hydrometallurgical processes, preferably in R.I.P. processesor in in-situ leaching processes or for the work-up of water containingmetals of value, characterized in that monodisperse, macroporousintermediate base or strong base anion exchangers of type I or type II,preferably of type II, are used.

Compared to the ion exchangers used in the prior art, the monodisperse,macroporous, intermediate base or strong base anion exchangers of type Ior type II to be used according to the invention surprisingly displaysignificantly higher adsorption rates for the metals of value, inparticular for uranium, low pressure drops, have small mixing zones andrequire significantly smaller amounts of water.

In a particularly preferred embodiment, the monodisperse, macroporousintermediate base or strong base anion exchangers of type I or type IIto be used according to the invention serve to adsorb uranium fromaqueous solutions into which it has been leached by means of strongacids. When leached by means of strong acids or by means of concentratedsodium carbonate solutions, the uranium is preferably present as theuranyl ion (UO₂ ²⁺), particularly preferably as uranyl chloride, uranylphosphate, uranyl acetate, uranyl carbonate, uranyl sulphate or uranylnitrate, among which uranyl sulphate obtainable by leaching of theuranium-containing rock by means of sulphuric acid is particularlypreferred.

The invention therefore particularly preferably provides for the use ofmonodisperse, macroporous intermediate base or strong base anionexchangers of type I or type II, in particular of type II, for theadsorption of uranyl ions from the salts of uranium with strong acids orwith sodium carbonate, particularly preferably from uranyl sulphate oruranyl carbonate.

The preparation of monodisperse ion exchangers is known to those skilledin the art. A distinction is made between, apart from the fractionationof heterodisperse ion exchangers by sieving, essentially two directpreparation methods, namely injection or jetting and the seed feedprocess in the preparation of the precursors, the monodisperse beadpolymers. In the case of the seed feed process, a monodisperse feedwhich can be produced, for example, by sieving or by jetting is used.

For the purposes of the present patent application, the termmonodisperse refers to substances in which the uniformity coefficient ofthe distribution curve is less than or equal to 1.2. The uniformitycoefficient is the ratio of the parameters d 60 and d 10. D 60 describesthe diameter at which 60% by mass of the particles in the distributioncurve are smaller and 40% by mass are larger or equal. D 10 refers tothe diameter at which 10% by mass of the particles in the distributioncurve are smaller and 90% by mass are larger or equal.

The monodisperse bead polymer, viz. the precursor of the ion exchanger,can be prepared, for example, by reacting monodisperse, optionallyencapsulated monomer droplets comprising a monovinylaromatic compound, apolyvinylaromatic compound and also an initiator or initiator mixtureand in the case of the present invention a porogen in aqueoussuspension. To obtain macroporous bead polymers for preparingmacroporous ion exchangers, the presence of a porogen is absolutelynecessary. Prior to the polymerization, the optionally encapsulatedmonomer droplet is doped with a (meth)acrylic compound and subsequentlypolymerized. In a preferred embodiment of the present invention,microencapsulated monomer droplets are therefore used for the synthesisof the monodisperse bead polymer. The various methods of preparingmonodisperse bead polymers both by the jetting principle and by the seedfeed principle are known to those skilled in the art from the prior art.Reference may at this point be made to U.S. Pat. No. 4,444,961, EP-A 0046 535, U.S. Pat. No. 4,419,245 and WO 93/12167.

The functionalization of the monodisperse bead polymers obtainableaccording to the prior art to give monodisperse, macroporous anionexchangers of type I or type II is likewise known to those skilled inthe art from the prior art.

Thus, EP-A 1 078 688 describes the preparation of monodispersemacroporous anion exchangers by the phthalimide process, in which

a) monomer droplets comprising at least one monovinylaromatic compoundand at least one polyvinylaromatic compound and, in the case of thepresent patent application, a porogen and/or optionally an initiator oran initiator combination are reacted to give a monodisperse, crosslinkedbead polymer,

b) this monodisperse, crosslinked bead polymer is amidomethylated bymeans of phthalimide derivatives,

c) the amidomethylated bead polymer is converted into an aminomethylatedbead polymer and

d) the aminomethylated bead polymer is finally alkylated.

In contrast to this ether/oleum variant, the preparation of monodispersemacroporous anion exchangers by the phthalimide process using the estervariant is known from EP-A 0 046 535. Here, the encapsulated beadpolymer comprising macroporous, divinylbenzene-crosslinked polystyreneis converted without prior removal of the capsule wall into a stronglybasic anion exchanger by the process described in U.S. Pat. No.3,989,650 by means of amidomethylation using phthalimidomethyl acetate,alkaline hydrolysis and quaternization using chloromethane.

In an alternative embodiment, the monodisperse macroporous anionexchangers used according to the invention can also be prepared by thechloromethylation process described in EP 0 051 210 B2, in which thebead polymers are haloalkylated by means of chloromethyl methyl etherand the haloalkylated polymer is reacted with ammonia or primary aminessuch as methylamine or ethylamine or a secondary amine such asdimethylamine at temperatures of from 25° C. to 150° C.

The monodisperse macroporous anion exchangers of type I or type II to beused according to the invention can be synthesized by means of thesethree variants.

The macroporosity required for the anion exchangers to be used accordingto the invention is obtained as indicated above by the use of porogenduring the preparation of the bead polymer precursor. Suitable porogensare organic solvents which do not readily dissolve or swell the polymerobtained. Examples are hexane, octane, isooctane, isododecane, methylethyl ketone, butanol or octanol and their isomers. Porogens are inparticular organic substances which dissolve in the monomer but do notreadily dissolve or swell the polymer (precipitants for polymers), forexample aliphatic hydrocarbons (Farbenfabriken Bayer DBP 1045102, 1957;DBP 1113570, 1957).

As an alternative to aliphatic hydrocarbons, it is also possible,according to U.S. Pat. No. 4,382,124, to use alcohols having 4 to 10carbon atoms as porogens for preparing monodisperse, macroporous beadpolymers based on styrene-divinylbenzene. Furthermore, an overview ofthe preparative methods for macroporous bead polymers is given there.

The distinction between type I and type II anion exchangers has beendescribed in U.S. Pat. No. 4,430,308. For the purposes of the invention,type I resins are resins whose adsorbing sites are quaternary ammoniumgroups which are substituted by alkyl groups, preferably by C₁-C₄-alkylgroups, particularly preferably by methyl groups.

In contrast thereto, type II resins are ones in which the quaternaryammonium groups have not only alkyl group(s) but also at least onehydroxyalkyl group, preferably a hydroxy-C₁-C₄-alkyl group. The type IIresins are preferably ones which havemethylenehydroxyalkyldimethylammonium groups as functional groups, withthe hydroxyalkyl group having one or two carbon atoms. The type II anionexchangers which are preferably used according to the invention can beprepared by means of the three above-described variants using tertiaryamines, preferably dimethylethanolamine or dimethylmethanolamine, asamine.

Metals of value to be isolated according to the invention by means ofthe monodisperse, macroporous anion exchangers are preferably metals ofmain groups III to VI and of transition groups 5 to 12 of the PeriodicTable of the Elements. Preference is given to winning mercury, iron,titanium, chromium, tin, lead, cobalt, nickel, copper, zinc, cadmium,manganese, uranium, bismuth, vanadium, the platinum group elementsruthenium, osmium, iridium, rhodium, palladium, platinum and also thenoble metals gold and silver. According to the invention, particularpreference is given to using the monodisperse, macroporous anionexchangers for winning uranium.

Preferred processes for the use of the monodisperse, macroporous anionexchangers to be used according to the invention are resin in pulpprocesses or in-situ leaching processes, particularly preferably in-situleaching processes, or the work-up of any water containing metals ofvalue.

The monodisperse, macroporous anion exchangers to be used according tothe invention are used in appropriate plants of exploration companies.In the case of the winning of uranium which is particularly preferredaccording to the invention, the pageshttp://www.uraniumsa.org/processing/insitu.leaching.htm,http://www.nrc.gov/materials/fuel-cycle-fac/ur-milling.htm orIAEA-TECDOC-1239, “Manual of acid in situ leach uranium miningtechnology” of the IAEA (International Atomic Energy Agency) of August2001 give examples of possible configurations of apparatus of existingmines which employ the in-situ leaching process.

As indicated above, the monodisperse, macroporous anion exchangers oftype I or type II, in particular of type II, to be used according to theinvention surprisingly display a significantly higher adsorption ratefor the abovementioned metals of value, in particular for the winning ofuranium from in-situ leaching processes, compared to the prior art.

EXAMPLES Example 1

a) Preparation of the monodisperse, macroporous bead polymer based onstyrene, divinylbenzene and ethylstyrene

3000 g of deionized water were placed in a 10 l glass reactor and asolution of 10 g of gelatin, 16 g of disodium hydrogenphosphatedodecahydrate and 0.73 g of resorcinol in 320 g of deionized water wasadded and mixed in. The temperature of the mixture was brought to 25° C.A mixture of 3200 g of microencapsulated monomer droplets having anarrow particle size distribution and comprising 3.6% by weight ofdivinylbenzene and 0.9% by weight of ethylstyrene (used as commercialisomer mixture of divinylbenzene and ethylstyrene containing 80% ofdivinylbenzene), 0.5% by weight of dibenzoyl peroxide, 56.2% by weightof styrene and 38.8% by weight of isododecane (industrial isomer mixturehaving a high proportion of pentamethyl-heptane) was subsequently addedwhile stirring, with the microcapsule comprising a formaldehyde-curedcomplex coacervate of gelatin and a copolymer of acrylamide and acrylicacid, and 3200 g of an aqueous phase having a pH of 12 are added. Themean particle size of the monomer droplets was 460 μm.

The mixture was polymerized while stirring by increasing the temperatureaccording to a temperature programme commencing at 25° C. and finishingat 95° C. The mixture was cooled, washed on a 32 μm sieve andsubsequently dried at 80° C. under reduced pressure. This gave 1893 g ofa spherical polymer having a mean particle size of 440 μm, a narrowparticle size distribution and a smooth surface.

The polymer was chalky white in appearance and has a bulk density ofabout 370 g/l.

1b) Preparation of the amidomethylated bead polymer

2400 ml of dichloroethane, 595 g of phthalimide and 413 g of 30.0%strength by weight formalin were placed in a reaction vessel at roomtemperature. The pH of the suspension was adjusted to 5.5-6 by means ofsodium hydroxide. The water was subsequently removed by distillation.43.6 g of sulphuric acid were then added. The water formed was removedby distillation. The mixture was cooled. At 30° C., 174.4 g of 65%strength oleum was added, followed by 300.0 g of monodisperse beadpolymer prepared according to process step 1a). The suspension washeated to 70° C. and stirred at this temperature for a further 6 hours.The reaction liquor was taken off, deionized water was added andresidual amounts of dichloroethane were removed by distillation.

Yield of amidomethylated bead polymer: 1820 ml

Elemental composition determined by analysis: carbon: 75.3% by weight;hydrogen: 4.6% by weight; nitrogen: 5.75% by weight.

1c) Preparation of the aminomethylated bead polymer

851 g of 50% strength by weight sodium hydroxide solution and 1470 ml ofdeionized water were added to 1770 ml of amidomethylated bead polymerfrom Example 1b) at room temperature. The suspension was heated to 180°C. and stirred at this temperature for 8 hours.

The bead polymer obtained was washed with deionized water.

Yield of aminomethylated bead polymer: 1530 ml

The total yield, extrapolated, was 1573 ml

Elemental composition determined by analysis: carbon: 78.2% by weight;nitrogen: 12.25% by weight; hydrogen: 8.4% by weight.

Number of mol of aminomethyl groups per litre of aminomethylated beadpolymer: 2.13

Number of mol of aminomethyl groups in the total yield ofaminomethylated bead polymer: 3.259

A statistical average of 1.3 hydrogen atoms per aromatic ringoriginating from the styrene and divinylbenzene units were replaced byaminomethyl groups.

1d) Preparation of a monodisperse, macroporous anion exchanger havingdimethylaminomethyl groups=type I

1995 ml of deionized water and 627 g of 29.8% strength by weightformalin solution were added to 1330 ml of aminomethylated bead polymerfrom Example 1c) at room temperature. The mixture was heated to 40° C.It was subsequently heated to 97° C. over a period of 2 hours. A totalof 337 g of 85% strength by weight formic acid were added at thistemperature. The pH was subsequently set to 1 by means of 50% strengthby weight sulphuric acid over a period of 1 hour. At pH 1, the mixturewas stirred for another 10 hours. After cooling, the resin was washedwith deionized water and freed of sulphate and converted into the OHform by means of sodium hydroxide solution.

Yield of resin having dimethylamino groups: 1440 ml

The total yield, extrapolated, is 1703 ml

The product contains 2.00 mol of dimethylamino groups/litre of resin.

The total number of mol of dimethylamino groups in the total yield ofproduct having dimethylamino groups was 3.406.

Example 2

Preparation of a monodisperse intermediate base macroporous anionexchanger having dimethylaminomethyl groups and trimethylaminomethylgroups=type I

1220 ml of bead polymer bearing dimethylaminomethyl groups from Example1d), 1342 ml of deionized water and 30.8 g of chloromethane were placedin a reaction vessel at room temperature. The mixture was heated to 40°C. and stirred at this temperature for 6 hours.

Yield of resin bearing dimethylaminomethyl groups andtrimethylaminomethyl groups: 1670 ml

The extrapolated total yield was 2331 ml.

Of the nitrogen-containing groups of the product, 24.8% were present astrimethylaminomethyl groups and 75.2% were present asdimethylaminomethyl groups.

The utilizable capacity of the product was: 1.12 mol/litre of resin.

Stability of the resin in the original state: 98 perfect beads in 100

Stability of the resin after the rolling test: 96 perfect beads in 100

Stability of the resin after the swelling stability test: 98 perfectbeads in 100

94 percent by volume of the beads of the final product had a size in therange from 0.52 to 0.65 mm.

Example 3

Preparation of a monodisperse strong base macroporous anion exchangerhaving hydroxyethyldimethylaminomethyl groups=type II

1230 ml of the resin having dimethylaminomethyl groups prepared asdescribed in Example 1d) and 660 ml of deionized water were placed in areaction vessel. 230.5 g of 2-chloroethanol were added thereto over aperiod of 10 minutes. The mixture was heated to 55° C. A pH of 9 was setby pumping in 20% strength by weight sodium hydroxide solution. Themixture was stirred at pH 9 for 3 hours, the pH was subsequently set to10 by means of sodium hydroxide solution and the mixture was stirred atpH 10 for a further 4 hours. After cooling, the product was washed withdeionized water in a column and 3 bed volumes of 3% strength by weighthydrochloric acid were then filtered through.

Yield: 1980 ml

The utilizable capacity of the product was: 0.70 mol/litre of resin.

Stability of the resin in the original state: 96 perfect beads in 100

Stability of the resin after the rolling test: 70 perfect beads in 100

Stability of the resin after the swelling stability test: 94 perfectbeads in 100

94 percent by volume of the beads of the end product had a size in therange from 0.52 to 0.65 mm.

Example 4

Preparation of a heterodisperse, strong base macroporous anion exchangerhaving trimethylammonium groups based on styrene-divinylbenzeneaccording to the prior art

4a) Preparation of the bead polymer—use of the initiator dibenzoylperoxide

1112 ml of deionized water, 150 ml of a 2% strength by weight aqueoussolution of methylhydroxyethylcellulose and 7.5 gram of disodiumhydrogenphosphate×12 H₂O were placed in a polymerization reactor at roomtemperature. The total solution was stirred at room temperature for onehour. The monomer mixture comprising 59.61 g of 80.53% strength byweight divinylbenzene, 900.39 g of styrene, 576 g of isododecane and7.70 g of 75% strength by weight dibenzoyl peroxide was subsequentlyadded. The mixture was firstly left to stand at room temperature for 20minutes and was then stirred at room temperature at a stirring speed of2000 rpm for 30 minutes. The mixture was heated to 70° C., stirred at70° C. for a further 7 hours, then heated to 95° C. and stirred at 95°C. for a further 2 hours. After cooling, the bead polymer obtained wasfiltered off and washed with water and dried at 80° C. for 48 hours.

The diameter of the beads was in the range from 0.32 to 0.71 mm.

4b) Preparation of the amidomethylated bead polymer

1331 ml of 1,2-dichloroethane, 493.9 g of phthalimide and 347.4 g of29.6% strength by weight formalin were placed in a reaction vessel atroom temperature. The pH of the suspension was adjusted to 5.5-6 bymeans of sodium hydroxide. The water was subsequently removed bydistillation. 36.2 g of sulphuric acid were then added. The water formedwas removed by distillation. The mixture was cooled. At 30° C., 132.3 gof 65% strength oleum was added, followed by 317.1 g of heterodispersebead polymer prepared according to process step 4a). The suspension washeated to 70° C. and stirred at this temperature for a further 6.5hours. The reaction liquor was taken off, deionized water was added andresidual amounts of dichloroethane were removed by distillation.

Yield of amidomethylated bead polymer: 1410 ml

Elemental composition determined by analysis: carbon: 76.8% by weight;hydrogen: 5.0% by weight; nitrogen: 5.4% by weight.

4c) Preparation of the aminomethylated bead polymer

1515.75 g of 24.32% strength by weight sodium hydroxide solution wereadded to 1385 ml of amidomethylated bead polymer from Example 4b) atroom temperature. The suspension was heated to 180° C. over a period of2 hours and stirred at this temperature for a further 8 hours.

The bead polymer obtained was washed with deionized water.

Yield of aminomethylated bead polymer: 1200 ml

Elemental composition determined by analysis: carbon: 79.3% by weight;nitrogen: 11.2% by weight; hydrogen: 8.4% by weight; balance oxygen.

Aminomethyl group content of the resin: 2.34 mol/l

A statistical average of 1.17 hydrogen atoms per aromatic ringoriginating from the styrene and divinylbenzene units were replaced byaminomethyl groups.

4d) Preparation of the heterodisperse, strong base, macroporous anionexchanger having trimethylammonium groups

1160 ml of aminomethylated bead polymer from Example 4c) were introducedinto 1950 ml of deionized water in an autoclave at room temperature.501.6 g of chloromethane were added and the suspension was heated to 40°C. At 40° C., the suspension was stirred at a stirring speed of 200 rpmfor a further 16 hours. The autoclave was cooled and vented. The resinwas filtered off on a sieve, washed with water and transferred to acolumn. 200 ml of 5% strength by weight aqueous sodium chloride solutionwere added while swirling. The resin was subsequently classified toremove soluble and solid constituents.

Volume yield: 1620 ml

Stability of the resin in the original state: 99% of whole beads

Stability of the resin after the rolling test: 96% of whole beads

Stability of the resin after the swelling stability test: 98% of wholebeads

The diameter of the beads was in the range from 0.35 to 0.85 mm.

Example 5

Preparation of a monodisperse, strong base macroporous anion exchangerhaving trimethylammonium groups based on styrene-divinylbenzene

1513 ml of deionized water were placed in a reactor. 900 ml ofaminomethylated bead polymer from Example 1c) and 263 ml of 50% strengthby weight sodium hydroxide solution were added thereto at roomtemperature. 357 g of chloromethane are subsequently added and thesuspension was heated to 40° C. The suspension was stirred at 40° C. for16 hours and subsequently cooled to room temperature.

The suspension was poured onto a sieve and subsequently washed withdeionized water. The anion exchanger was then introduced into a columnprovided with a glass frit. 1500 ml of 3% strength by weight aqueous HClwere filtered through. The anion exchanger was then classified by meansof water to remove solid and dissolved particles.

Volume yield: 1560 ml

Stability of the resin in the original state: 99% of whole beads

Stability of the resin after the rolling test: 97% of whole beads

The diameter of the beads was in the range from 0.57 to 0.67 mm.

Example 6

Determination of the uptake capacity of a heterodisperse, strong basemacroporous anion exchanger having trimethylammonium groups based onstyrene-divinylbenzene

500 g of a zinc(II) chloride solution which was adjusted to pH 1 bymeans of hydrochloric acid were placed in a polyethylene bottle. Thesolution contained 4.2 g of zinc per litre of solution. 10 ml of aheterodisperse, strong base macroporous anion exchanger havingtrimethylammonium groups based on styrene-divinylbenzene were added tothe solution. The mixture was stirred at room temperature for 24 hours.

Samples were taken after 5 hours and 24 hours and analysed to determinetheir zinc content.

Sample taken after 5 hours: zinc content=4.2 g of zinc per litre ofsolution—based on the initial concentration, 0% of zinc was taken up.

Sample taken after 24 hours: zinc content=4.1 g of zinc per litre ofsolution—based on the initial concentration, 2.5% of zinc was taken up.

Example 7

Determination of the uptake capacity of a monodisperse, strong basemacroporous anion exchanger having trimethylammonium groups based onstyrene-divinylbenzene

500 g of a zinc(II) chloride solution which was adjusted to pH 1 bymeans of hydrochloric acid were placed in a polyethylene bottle. Thesolution contained 4.2 g of zinc per litre of solution.

10 ml of a monodisperse, strong base macroporous anion exchanger havingtrimethylammonium groups based on styrene-divinylbenzene were added tothe solution. The mixture was stirred at room temperature for 24 hours.

Samples were taken after 5 hours and 24 hours and analysed to determinetheir zinc content.

Sample taken after 5 hours: zinc content=3.5 g of zinc per litre ofsolution—based on the initial concentration, 16.7% of zinc was taken up.

Sample taken after 24 hours: zinc content=3.3 g of zinc per litre ofsolution—based on the initial concentration, 26.7% of zinc was taken up.

Methods of examination:

Number of perfect beads after preparation

100 beads are viewed under the microscope. The number of beads whichhave cracks or display spalling is determined. The number of perfectbeads is the difference between the number of damaged beads and 100.

Determination of the stability of the resin after the rolling test

The bead polymer to be tested is distributed in a layer of uniformthickness between two plastic cloths. The cloths are placed on a firm,horizontal substrate and subjected to 20 cycles in a rolling apparatus.One cycle consists of one forward and back movement of the roller. Afterrolling, the number of unscathed beads in 100 beads is determined onrepresentative samples by counting under the microscope.

Swelling stability test

25 ml of anion exchanger in the chloride form are introduced into acolumn. 4% strength by weight aqueous sodium hydroxide solution,deionized water, 6% strength by weight hydrochloric acid and once againdeionized water are introduced in succession into the column, with thesodium hydroxide solution and the hydrochloric acid flowing downwardsthrough the resin and the pure water being pumped through the resin frombelow. The treatment is sequenced by means of a control apparatus. Onecycle takes one hour. 20 cycles are carried out. After the end of thecycles, 100 beads are counted out from the resin sample. The number ofperfect beads which are not damaged by cracks or spalling is determined.

Utilizable capacity of strong base and intermediate base anionexchangers

1000 ml of anion exchanger in the chloride form, i.e. the nitrogen atombears chloride as counterion, are introduced into a glass column. 2500ml of 4% strength by weight sodium hydroxide solution are filteredthrough the resin over a period of 1 hour. The resin is subsequentlywashed with 2 litres debasified, i.e. decationized, water. Water havinga total anion hardness of 25 degrees of German hardness is then filteredthrough the resin at a rate of 10 litres per hour. The eluate isanalysed to determine the hardness and also the residual amount ofsilicic acid. Loading is complete at a residual silicic acid content of≧0.1 mg/l.

The number of gram of CaO taken up by one litre of resin is determinedfrom the amount of water filtered through the resin, the total anionhardness of the water filtered through and the amount of resininstalled. The number of gram of CaO represents the utilizable capacityof the resin in the unit gram of CaO per litre of anion exchanger.

Volume change chloride/OH form

100 ml of anion exchanger bearing basic groups are rinsed into a glasscolumn by means of deionized water. 1000 ml of 3% strength by weighthydrochloric acid are filtered through over a period of 1 hour and 40minutes. The resin is subsequently washed free of chloride withdeionized water. The resin is rinsed under deionized water in a tampingvolumeter and jiggled in until the volume was constant—volume V1 of theresin in the chloride form.

The resin is again transferred into the column. 1000 ml of 2% strengthby weight sodium hydroxide solution are filtered through. The resin issubsequently washed free of alkali with deionized water until the eluatehas a pH of 8. The resin is rinsed under deionized water in a tampingvolumeter and jiggled in until the volume is constant—volume V2 of theresin in the free base form (OH form).

Calculation: V1−V2=V3

V3:V1/100=swelling change chloride/OH form in %

Determination of the amount of basic aminomethyl groups in theaminomethylated, crosslinked polystyrene bead polymer

100 ml of the aminomethylated bead polymer are jiggled in on a tampingvolumeter and subsequently rinsed into a glass column by means ofdeionized water. 1000 ml of 2% strength by weight sodium hydroxidesolution are filtered through over a period of 1 hour and 40 minutes.Deionized water is subsequently filtered through until 100 ml of eluateadmixed with phenolphthalein have a consumption of not more than 0.05 mlof 0.1 N (0.1 normal) hydrochloric acid.

50 ml of this resin are admixed with 50 ml of deionized water and 100 mlof 1 N hydrochloric acid in a glass beaker. The suspension is stirredfor 30 minutes and subsequently introduced into a glass column. Theliquid is drained. A further 100 ml of 1 N hydrochloric acid arefiltered through the resin over a period of 20 minutes. 200 ml ofmethanol are subsequently filtered through. All eluates are collectedand combined and titrated with 1 N sodium hydroxide against methylorange.

The amount of aminomethyl groups in 1 litre of aminomethylated resin iscalculated according to the following formula: (200−V)·20=mol ofaminomethyl groups per litre of resin.

Determination of the degree of substitution of the aromatic rings of thecrosslinked bead polymer by aminomethyl groups

The amount of aminomethyl groups in the total amount of theaminomethylated resin is determined by the above method.

The number of mol of aromatics present in the amount of bead polymerused, A in gram, is calculated from this amount by division by themolecular weight.

For example, 950 ml of aminomethylated bead polymer containing 1.8 molof aminomethyl groups per litre are prepared from 300 gram.

950 ml of aminomethylated bead polymer contain 2.82 mol of aromatics.

1.8/2.81=0.64 mol of aminomethyl groups are then present per aromatic.

The degree of substitution of the aromatic rings of the crosslinked beadpolymer by aminomethyl groups is 0.64.

1. A method of using monodisperse, macroporous anion exchangers of typeI or type II for winning metals of value, wherein type I denotes resinswhose adsorbing sites are quaternary ammonium groups which aresubstituted by alkyl groups, preferably C₁-C₄-alkyl groups, and whereintype II denotes resins in which the quaternary ammonium groups have notonly alkyl group(s) but also at least one hydroxyalkyl group, preferablya hydroxy-C₁-C₄-alkyl group.
 2. A method according to claim 1, whereinthe metals of value belong to main groups III to VI or transition groups5 to 12 of the Periodic Table of the Elements.
 3. A method according toclaim 2, wherein the metal of value is uranium.
 4. A method according toany of claims 1 to 3, wherein the monodisperse macroporous anionexchangers are used in resin in pulp processes or in in-situ leachingprocesses or in the work-up of water containing metals of value.
 5. Amethod according to claim 3, wherein the uranium is present as uranylchloride, uranyl phosphate, uranyl acetate, uranyl carbonate, uranylsulphate or uranyl nitrate.
 6. A process for winning metals of value bythe resin in pulp process or the in-situ leaching process or from watercontaining metals of value, wherein monodisperse, macroporous anionexchangers of type I or type II, preferably of type II, are used, andtype I denotes resins whose adsorbing sites are quaternary ammoniumgroups which are substituted by alkyl groups, preferably C₁-C₄-alkylgroups, and type II denotes resins in which the quaternary ammoniumgroups have not only alkyl group(s) but also at least one hydroxyalkylgroup, preferably a hydroxy-C₁-C₄-alkyl group.
 7. A process according toclaim 6, wherein the anion exchangers of type II are functionalized bytertiary amines, preferably dimethylethanolamine ordimethylmethanolamine.
 8. A process according to claim 6 or 7, whereinmetals of value of main groups III to VI and transition group 5 to 12 ofthe Periodic Table of the Elements are won.
 9. A process according toclaim 6, wherein uranium is won as metal of value.